\documentclass[12pt]{article}  
 \textheight15cm \textwidth11cm \parindent0mm \parskip 1ex plus2ex minus0.8ex
\begin{document}
\parindent 0mm
\newcounter{floornumber}
\newcounter{roomnumber}[floornumber]
\newcommand{\floor}[1]{\stepcounter{floornumber}\par\vspace{3ex}%
                        {\bf\arabic{floornumber}. floor: #1}\newline}
\newcommand{\room}[1]{\stepcounter{roomnumber}\hspace*{2em}%
                        room no.\ \arabic{roomnumber}: #1\newline}
\floor{Standard}
 \room{blue apartment}
 \room{velvet apartment}
\floor{Exclusive}
 \room{President suite}
 \room{Royal suite}

 the same example, but modified:
 room-numbers with 3 digits, 1st digit indicates the floor
\parindent 0mm
\newcounter{floornr}
\newcounter{roomnr}
\newcounter{hundreds}
\newcommand{\Floor}[1]{\stepcounter{floornr}\par\vspace{3ex}%
                       \addtocounter{hundreds}{100}
                       \setcounter{roomnr}{\value{hundreds}}
                        {\bf\arabic{floornr}. floor: #1}\newline}
\newcommand{\Room}[1]{\stepcounter{roomnr}\hspace*{2em}%
                        room no.\ \arabic{roomnr}: #1\newline}
\Floor{Standard}
 \Room{blue apartment}
 \Room{velvet apartment}
\Floor{Exclusive}
 \Room{President suite}
 \Room{Royal suite}
\end{document}
